The invention relates to a motor vehicle door lock comprising a locking mechanism as well as an opening drive acting on the locking mechanism, an operating lever mechanism and at least one sensor for checking an operator opening request as well as a safety device, which prevents opening of the locking mechanism at least in its “safe” position.
The opening drive of such motor vehicle door locks generally provides the so-called electric opening of the locking mechanism. In such an arrangement, a handle, such as an external operating lever and/or an internal operating lever, is not mechanically connected to the locking mechanism. Instead the sensor activated by an operator in case of a respective operator opening request ensures that the opening drive or the electric drive for opening the locking mechanism is supplied with current. As a result, the locking mechanism is opened by the motor and not by manual action. This is, in most cases, achieved by the opening drive pivoting a triggering lever, which in turn lifts a pawl off a rotary latch, being respective components of the locking mechanism.
Apart from the term “electric opening” respective literature also makes reference to “Open by Wire” in this context (see “Kraftfahrtechnisches Taschenbuch” published by Bosch, 24th edition, Apr. 2002, page 896 ff.). A considerable advantage of such systems is the option of being able to provide a so-called “Passive Entry” access to the respective motor vehicle. Such mechanisms require very fast unlocking actions or so-called “overtaking solutions”. The “overtaking principle” refers to a process in which the opening drive has already opened the locking mechanism or has lifted the respective pawl off the rotary latch although a preceding unlocking action has not been fully completed. Consequently operators do not experience any waiting times.
A typical example for a motor vehicle door lock or a motor vehicle door lock with the described functionality for electric opening is disclosed and described in EP 1 320 652 B1. At this point, a distinction is made between a normal and an emergency operation. During normal operation, the electric drive acts on the locking mechanism for electric opening and ensures that in at least the emergency operation, the locking mechanism is mechanically opened. The emergency operation typically corresponds to an emergency opening, which is or can be required if the electric drive does no longer operate reliably or operate at all due to a drop of voltage in the vehicle. According to the known teaching and as part of the emergency operation, a mechanical operation—emergency opening—of the locking mechanism is then still possible.
A generic motor vehicle door lock is disclosed in DE 197 06 393 B4 in which different control electronics and respective signaling devices are employed. A centre-zero switch is, for instance provided on the external and the internal door handle. In addition, also the position of a child lock device as a safety device is sensed with the aid of a child lock switch. If the child lock has been applied, activation of the centre-zero switch or sensor on the internal door handle does not produce an opening signal and consequently does not cause the impinged sensor to respectively trigger the opening drive. This generally has proven to be successful.
The generic teaching of DE 197 06 393 B4 discloses a complex functionality and therefore contains various sensors for checking the safety device and the handle (internal and external handle). This results in a plurality of components being required for realizing the known motor vehicle door lock. In addition, the numerous sensors must be connected to one or several control units for evaluating their signals and controlling the opening drive. Currently this is typically achieved with the aid of so-called component carriers including respective printed conductor arrangement. In many cases, this printed conductor arrangement is designed as a lead frame requiring a complex production and installation for the reasons described in the teaching.
This means that the complex functionality of the teaching of the prior art disclosed in DE 197 06 393 B4 does not only require a plurality of sensors but also, an elaborate printed conductor arrangement in order to connect the sensors to a respective control unit or to each other and in order to actually mechanically produce all required functional states. The result is a relatively high manufacturing cost. Although this can be partly justified by the extra level of comfort offered by the “Passive Entry” function, cost pressures in the automotive sector are considerable, so that more price-effective solutions are required. The invention aims to provide a solution for this.